Cushioning and silencing mechanical tappet



Oct. 28, 952 J. w. HUMPHREYS 2,615,439

cusmomfqs AND SILENCING MECHANICAL TAPPET Filed Nov. 28. 1949 I /V/J/ )m'a luvi-zu'rbri- JOHN'W. HuMPHREYs BY Q tf Awwoauevs Patented Oct. 28,

1 Yum-TED: PATENT "OFFICE" I I I cosmoiwf casb sfiafizmcMEcnAmcAt J ohn" W.; HumpIireyaLMuSkegon; Mich, .assig nor s to-Johnson Products; Inc., .Muskegon, Mich a corporation of Michigan Application Novein'br28, 1949', see-aim; 129,796

This invention is f-directed to and is concerned I with mechanical tappets used:between: operat-' ing cam shafts and'valvesininternal combustion engines; for controllingi the opening: and closing Of such-valVesduring 'ehginecp'eration. r v

It is an object and purpose of the present -in vention to provide ainechanical tappet which is" automatically self-adjustable during engine operation to maintain pressure contact between ingflafter the engine was'fully warmed up if a close contact of the tappet' with said valve'stems or push rodswas maintained when the engine was cold.- Usually with mechanical tappets; a:

clearance "or toleranceis providedin adjusting the tappets wit-h reference to the push' rods or valve stems which amounts tofa :few'thousandth's ofan inch and is prese'ntgfor example; between the upper end ofa tappethndth'e lower'e'nd of a valve stem when'the valveis closed; such clea'r ance or tolerances usuallybeing made by introducing a shimof the few thousandthsof an'inch and-the lower end 0fthe valvestefn' when 'the adjustment is -madei Thus when the engine-is started after it has cooled,the' tappetwhen elevated to lift a valve by direct contactwith the lower end of a valve stem'above it; orto de'press and lower a' valve in the overhead'valve' en- L thickness between the upper end of the tappet gines, moves this distance before 'striking the end of a valve stemabove it,'or "the upperend of such valve stem inoverhead gengines;causing metallic noises which-have been given the name of tappet noises; but which' disappear asthe en gine'is warmed up and the longitudinal expansion'of the parts 'eliminates 's'uch clearance 'or tolerance gap which wa's left when the adjustment was made 1 Y Y Elimination of the tappet' noisesfwhich come from metal striking against metal whenanengine is started=after it has cooled to a lower temperature th'a'n'its'ru'nning temperature; is taken care of by hydraulic-tappets.-- such tappets'how-f ever a'reexp'ensivefboth in-'-the**structure'of thespleens; (01. 123-90) of the engine so that such tappetsar normally used onlyin thehigher priced makes o-fau'toi mobiles.- Even with' such hydraulic 'tappets there is' a very short or limited period of tappet noises when an engine'is started; less-in length than the production of the tapp'et noises with the ordinary mechanical tappet; because the hydraulic 'tappet' must be supplied with oilpumped by the-"tappet structureto extend the-length of the tappet' during the' first few rotations of the engine crank shaft before direct contact elimihating tappet noises is accomplished.

Themecha'nical tapp'et which is the subject matter of the present invention, like th atshown in another form in afcop'ending application of even date filed by me; includes anovelstructur which maintains the "direct "cohtact'of thetappet or "an' adjusting serewcarriedby' it with the v lower end of avalve stern in'one" ty'pe'of engine and of the rocker arm with "the upper-end of the valve 'stem with the? overhead valve engine. Upon longitudinal expansion or elongation due to" temperature rise's'the no vel mechanism in the tappet decreases in distance so that the valves are not held open when'thy should be closed such decrease in dimension ccurring automat many and equalling'the longitudinal expansion caused by higher temperatures, p g

In the invention; a pr actical, veryuseful and simple mechanism for the automatic adjustment of the tappet; to conform to-expansioncaused by" rising' ternperatures and-contraction caused by lowering temperatures, is provided and'a mechanical tappet is made which. serves, all the purposes and effects of a hydraulic tappet, is. manufactured a-t far-less cost and is installed with no extra cost over present mechanical tappets. At any timewhen 'the tappet adjustment is m'ade-no shims fror tappetlc-learance or tolerance are used. "Ihebearing end is adjusted for direct contact engagement with either the push rod or the valve stem. 7

An understandingiofthe invention' may be had-- frontthe following Idescri'ption, taken in -con= nection with the accompanying drawing; 5

which. 7

' Fig.1'1 is apartial side elevation arid longitu dinal vertical section substantially," on thep1ane of line |'l oi -Fig. :Bfthrbiigh the upper end of a tappet made=in =accordane with'rny'invent' a, with the tappet partsoccupyingthepositiohs which they take when the engine is sold,"

Fig. 2 is a similar partial' e1evati' end-section showing the adj ust'mnt wmentakenfplacef after the enginehas beenrunnirig and its tem perature raisediand" FieLe isf'a horizontal-""s 5e watery.

Like reference characters refer to like parts in the difierent figures of the drawing.

In the-structure of the tappet illustrated, a generally cylindrical tappet body I has vertical walls which surround an open center, the lower end of the tappet being closed and its upper end being open. Preferably, an annularshoulder 2 is provided between the ends of the tappet and interiorly thereof by a ring cast with the tappet body. Such tappet body is mounted for reciprocation in a suitable guide 3 therefor cast with the engine block or on a tappet guide member permanently fastened thereto.

In the upper portion of the tappet body a cylindrical block 4 is inserted until it rests upon the support provided by the annular shoulder 2. A vertical sleeve 5 is inserted in the upper end of the tappet body, its lower end resting upon the block 4. For all functional purposes the two parts 4 and 5 could be integral, as they have no movement with respect to each other, but are made separate for greater ease in manufacture. Within the sleeve 5, a piston member is mounted for upward and downward movement having a solid upper end or head 6 and an annular skirt I depending therefrom. The tappet is shown in conjunction with a push rod 8 to operate an overhead valve. Rod 8, at its lower end, has a head 8a of generally semispherical form partially entering a complementary concave recess in the upper side of the piston head 6. The piston B, I is subjected to pressure from the rod 8 which in turn transmits force from the heavy valve spring used with each intake and exhaust valve in internal combustion engines, such pressure occurring when an engine valve is opened.

In the upper side of the block 4 radial recesses are made, having arcuate bottoms 9, which are spaced radially around the vertical center of the block 4 and extend outwardly as shown. Each of said recesses, four being shown in the disclosure made though the number may be varied, receives the lower end portion In of an adjustable element, the lower end edge of which is of arcuate form conforming to the bottoms 9 of such recesses. Each of said lower end portions I terminates at its outeredge in an upwardly and outwardly extending short finger II. The lower end of the skirt I of the piston within the sleeve reaches to and rests upon the fingers I I. The outwardly extending portions of the adjusting members, indicated at 12, progressively decrease in width upwardly, and each terminates in an outwardly and upwardly turned finger at l3, the upper inner corner of which is rounded and curved and bears against an inclined side of a downwardly extending frusto-conical projection l4 located centrally and extending at the lower side of the head 6 of the piston. The projection l4 may be either frusto-conical or frustopyramidal. An endless coiled tension spring l5, under tension, is located around all of the intermediate portions 12 of the adjusting members below the fingers 13 as shown, the tendency of which is to draw said adjusting members at their upper end portions toward each other to the position shown in Fig. 1.

When the temperature of an engine which has been operating lowers upon stopping it, and the push rod 8 and other parts associated with it contract because of reduction in temperature, the movement of the adjusting members from a position, such as shown in Fig. 2, to that shown in Fig. 1, moves the piston 6 and skirt I up-- wardly to maintain the parts in contactwith 4 the head So. When the engine is started and the temperature of the engine block and other parts associated with it --rises, uponlongitudinal increase in dimension of the push rod 8 and of the valve stem and other associated parts, the elongation which occurs, coupled with the vibratory shocks of operation of the push rod forces the piston 6 and skirt I downward and turns the adjusting members outwardly at their upper ends thereby stretching the spring [5 with a maintenance of the direct, intimate contact of the head 8a with the piston head 6 which eliminates tappet clicking noises. It will be understood that, by this structure and through its operation, contact is made at all times between the head Be on the push rod and the head 6 of the piston. When the engine is cold the contraction in. lengthv of the push rod, which is relatively long, and of other parts in a vertical direction, is taken up by the piston 6 being pushed upwardly, as in Fig. 1, to engage such head 8a. .With the longitudinal expansion of the push rod 8 and of other parts associated therewith, the piston 6 is forced downwardly, and when the engine is fully warmed, has reached the position shown in Fig. 2, moving the adjusting members l2 outwardly. Between cold and hot conditions or the engine, the piston may occupy intermediate positions between those shown in Figs. 1 and 2 but always maintaining contact with the head 80. of the push rod.

Normally, the clearance between the push rod (or valve stem) at which a tappet is adjusted, will be a few thousandths of an inch, varying in different models of engines. With every reciprocation of a tappet, on its upward movement there will be a movement which first closes such clearance, and a pronounced sound from metal striking on metal. Such clearance will progressively decrease as the engine warms up until, at its fully warmed running condition, the clearance will be taken up if there has been proper adjustment, and contact of the end of the push rod with the tappet maintained.

With the present invention this complete contact of the tappet piston 6 with the push rod is maintained when the engine is cold or hot, or at any intermediate condition between. The striking of metal against metal, in an open air position so that the noises thereof may be transmitted readily is avoided. Any metal to metal contact of the skirt I of the piston with the fingers H, or the ends of the parts [3 with the upper portion of the piston skirt I, takes place within the tappet and all noise of such contact is substantially smothered.

It is of course to be understood that the angle of the sides 14 to the horizontal is variable. In general with metal to metal bearing, such as the edges of the adjusting members I2 with the inclined sides I 4 of the projection, if the angle between them is approximately 9 degrees or less there will be a slowing up and resistance of movement of one upon the other. This is well known to all those skilled in the art; and such resistance to the outward movement of the rocking adjusting members In from the position in Fig. 1 to that shown in Fig. 2, plus the resistance of the spring l5, causes the outward movements of the adjusting members 12 at their upper ends to be sluggish. All release of pressure of the push rod against the piston 6, when an engine valve sets against its seat, gives the spring 65 full freedom of contraction to tend to draw the rocking adjusting members l2 inwardly toward each other at their upper ends, and this tendency will be furthered by engine vibration in operation.

It is to be understood that with overhead valves the usual manual adjustment between the rocker arm and the upper end of the push rod is used and at any time that this manual adjustment is resorted to, it is for the purpose of taking up slack if necessary between the head 8a and the piston head 6 when the engine valves are closed, or of relieving pressure of the head 8 against the piston head 6 if necessary for closure of the engine valve actuated thereby if the engine valve is not closed as it should be at its intended closing position. It is further to be understood that the tappet of the present construction may be used with engine valves in the other mentioned type of engine, in which the lower end of the valve stem extends toward and ordinarily bears against an adjusting screw threaded into the upper end of the tappet which adjusting screw, with the present invention, would be threaded into the piston head 6, using any preferred or desired manually operated adjusting screw.

The structure of tappet is self-adjusting under engine operating conditions and with it an elimination of the tappet clicking noises is attained at all times irrespective of the engine temperature. All of the advantages, at a great reduction of expense of hydraulic tappets are present. The tappet operates in some respects in accordance with the principles of operation of hydraulic tappets, using the same cams on cam shafts as are used with hydraulic tappets. There is no interval of time, even of short length, before tappet noises are eliminated as in hydraulic tappets, but the tappet noises are eliminated at all times not only at the start of engine operation but throughout its operation.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. A tappet comprising, a hollow body adapted to be mounted for reciprocation said body having a closed end and an open end, a supporting member located transversely of the body between its ends and at the side thereof toward the open end of the body having a plurality of arcuate guides extending radially outward from the center of said supporting member, vertical adjusting members, one seatedin each guide and extending away therefrom adapted to rock in'said guides to move away from or toward each other, each of said adjusting members having an outwardly extending lower portion, yielding means normally drawing them toward each other, and a piston having a head and a depending skirt mounted for movement in the direction of the length of said body having the lower end of the skirt resting upon said outwardly extending lower portions of said adjusting members, the head of said piston at its inner side having a depending centrally disposed cam projectin between the adjacent ends of said adjusting members, the

rocking of said adjusting members toward each other under influence of said yielding means moving the piston outward, and. said members moving away from each other under pressure and vibrating forces applied to the outer side of the piston head and transmitted therefrom to said adjusting members, thereby separating said adjusting members and permitting the piston to move inwardly. I

2. A tap-pet comprising, an elongated hollow tappet body open at one end and closed at the other, said tappet body being mounted for longitudinal reciprocatory movements, a transverse supporting member within the body between its ends fixed in relation to the body, the side of the supporting member toward the open end of the body having a plurality of arcuate grooves therein extending radially outward from the central portion of said supporting member and spaced from each other, adjusting members having inner end portions seated in said grooves, and an outer portion extending away from the grooves, a circular resilient member surrounding the outer portions of said adjusting members normally drawing them toward each other at their outer portions, a piston having a head and a skirt, said head being located over the outer ends of said adjusting members and said skirt extending inwardly around the outer portions thereof, each of said adjusting members at its lower end portion terminating in a finger against which the lower edge of the skirt bears.

3. A structure as defined in claim 2, the outer portion of each of said adjusting members at the inner corner thereof having an arcuate form and said head at its'inner side having a centrally disposed projection with inclined sides extending from said piston inwardly toward the center of.

said piston to bear against said rounded corners of the adjusting members.

4. A structure defined in claim 2, and a guide sleeve within the tappet body resting at its inner end upon said supporting member and surrounding said piston.

5. A tappet comprising, an elongated cylindrical hollow body having a closed lower'end and an open end, a supporting member located within said body transversely thereof between its ends in fixed relation to the body, a second member between said supporting member and the open end of the body, a guide for said second member within the body bearing at its inner end against the transverse supporting member and surrounding said second member, and adjusting members mounted lengthwise of the body between said supporting member and said second member and mounted for rocking movements at their lower ends engaging with both said supporting and sec- REFERENCES CITED The following-references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re.21,802 Russell May 13, 1941 1,123,142 Rich"; Dec. 29, 1914 1,806,099- .Thomas May 19, 1931 1,986,579

I Johnson 'Jan. 1, 1935 

